1. Field of the Invention
The present invention relates to a process for preparing a 2-cyanobiphenyl compound. More particularly, the present invention relates to a process for preparing a 2-cyanobiphenyl compound, which is useful as an intermediate of pharmaceuticals such as antihypertensives.
2. Discussion of the Related Art
Conventionally, there have been known processes for preparing 2-cyanobiphenyl compounds, including (A) a method of reacting a phenylmagnesium halide compound with a 2-halobenzonitrile in the presence of a manganese(II) halide (Japanese Patent Laid-Open No. Hei 6-9536); and (B) a method of reacting a phenylmagnesium halide compound with a 2-halobenzonitrile in the presence of a metal manganese and trimethylchlorosilane (Japanese Patent Laid-Open No. Hei 8-109143).
In the process (A), however, since the manganese(II) halide has hygroscopic property, there arises such a problem that much care is necessitated in handling.
In the process (B), since it is necessary to add an equimolar amount of a metal manganese to the 2-halobenzonitrile, the metal manganese has to be treated after terminating the reaction, thereby industrial wastes are generated. Therefore, this method is not industrially advantageous.
In addition, there have been known processes for preparing 4'-methyl-2-cyanobiphenyl, which is one of the 2-cyanobiphenyl compounds, including (C) a process for preparing 4'-methyl-2-cyanobiphenyl comprising treating a 4-methylphenylmagnesium halide and a 2-halobenzonitrile with a Ni catalyst in the presence of a zinc halide and an amine compound (Japanese Patent Laid-Open No. Hei 8-231454); and (D) a process for preparing 4'-methyl-2-cyanobiphenyl comprising reacting a phenylmagnesium halide with a zinc halide, and treating the resulting product with 4-bromobenzonitrile in the presence of a Ni catalyst (J. Org. Chem. 42. 1821, (1977)).
However, in the process (C), an expensive tertiary amine has to be used as an amine compound in order to give a reaction yield of at least 80%, and thereby there arise economical disadvantages.
In addition, in the process (D), an expensive bromide or iodide has to be used as a halide, which is a reaction substrate, and thereby there arise economical disadvantages as in the process (C).
In view of the problems in the prior art mentioned above, an object of the present invention is to provide a method for economically, advantageously, simply and industrially preparing a 2-cyanobiphenyl compound.
These and other objects of the present invention will be apparent from the following description.